What is juvenile dermatomyositis?

Juvenile dermatomyositis (JDM) is an autoimmune disease that affects children, usually between the ages of 2 and 15. An autoimmune disease is one in which the body’s immune system attacks its own healthy tissues and cells because it mistakenly sees them as invaders.

How common is juvenile dermatomyositis?

Juvenile myositis (which includes both juvenile dermatomyositis and the very rare juvenile polymyositis) affects about 3,000–5,000 children in the United States each year.

What causes juvenile dermatomyositis?

The cause of JDM is not known. It does not spread from one person to another. Researchers believe it may be a result of the body’s abnormal immune system response to a virus. Even after the virus is gone, the immune system continues to fight and ends up attacking the body itself. Researchers also believe that autoimmune disorders such as JDM may be inherited.

What are the symptoms of juvenile dermatomyositis?

The main symptoms of juvenile dermatomyositis are skin rashes, usually on the face, knuckles, elbows, and knees, and swelling and weakening muscles. This is caused by inflammation in the blood vessels (vasculitis), and also by swelling in the muscles. Other symptoms may include:

  • Red or purple coloring around the eyelids or cheeks
  • Puffy eyelids
  • Gradually weakening muscles (often in the neck, shoulders, trunk, back, or hips)
  • Fever
  • Sore and swollen joints
  • Fatigue
  • Difficulty with everyday activities, such as climbing stairs, standing up, riding a bicycle, getting dressed, lifting the head
  • Frequently falling down
  • Severe abdominal pain (because of ulcers in the digestive system due to the vasculitis)
  • Weak voice (dysphonia)
  • Difficulty swallowing (dysphagia)
  • Hardened lumps from deposits of calcium underneath the skin (calcinosis)
  • Muscle tightening and shortening, which can cause a joint to stay in a bent position

Because of these symptoms, the child may participate in fewer activities than other children. Sometimes the child may even be accused of being lazy.

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